periodic law

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

n. Chemistry The principle that the properties of the elements recur periodically as their atomic numbers increase.

from Wiktionary, Creative Commons Attribution/Share-Alike License

n. The principle that chemical properties of the elements are periodic functions of their atomic numbers

from the GNU version of the Collaborative International Dictionary of English

n. See under Periodic.

adj. the generalization that the properties of the chemical elements are periodic functions of their atomic wieghts. “In other words, if the elements are grouped in the order of their atomic weights, it will be found that nearly the same properties recur periodically throughout the entire series.” The following tabular arrangement of the atomic weights shows the regular recurrence of groups (under I., II., III., IV., etc.), each consisting of members of the same natural family. The gaps in the table indicate the probable existence of unknown elements.